Would a 48V 21AH battery, consisting of quantity 78 18650 lithium cells work well with that AW 35 amp controller? I could get that for $200.
No Chinese cells, only the best Panasonic cells! Nominal Capacity: 10.5Ah. 100% Genuine Panasonic cells. (no “knock offs”). Cycle life: 800+ cycles. The black outer case is not included. Resistance: ≤ 250mΩ.
www.ebay.com
No. The BMS is what matters. Cell count etc. has nothing to do with anything. Your not knowing that is a bad sign considering what it is you are thinking about. The headline says right off the bat its a 10.5ah pack. So I see where you are going with this: Buy two of them and parallel them together and that gives you your 78 cells and 21ah.
Most people will freak if you tell them you are going to try and parallel two packs together. But I have been doing it for years, personally. I know the benefits... and the dangers. And typically I tell people that paralleling packs is OK provided you know *exactly* what you are doing, and the risks and weaknesses that go with it... and paralleling packs is NOT for beginners. You plan to assemble these packs together and then charge them from a single lead I bet, right? You realize then that your charge to the second pack in line is going to be going thru the pack's output circuit, which means no BMS protection for stuff like overcharging a pack whose cells have a different capacity since they are not matched together from birth?
When you parallel two packs together and leave them together as one, you have to buy both packs brand-new, with identical cells, configurations, BMS'
and identical charge cycle counts (which means buy them new). Otherwise one or the other pack will be at a different stage in its life cycle and will not have an absolutely identical capacity, which it must have.
I haven't even touched on what you need to do to safely make the connection. Or what you have to do if you decide to charge separately, which is a pain in the ass and not worth the effort.
Paralleling two packs means the BMS limitations are multiplied by the number of packs in parallel, so a 30a peak BMS is now 60a. Thats a good thing, but its ONLY on paper. Try that in real life and reality bites back as the heat generated and the stress on the cells will still be the same on the individual packs. You are running them HARD doing this. I started doing bigass (30ah+) batteries specifically because of this issue with parallel'd packs on my 2wd bikes that ate power in serious quantities.
You are talking about increasing your level of risk significantly and you are going to do it with packs that have zero reason to inspire confidence.
- The vendor has a 100% rating but a whopping two transactions under their belt.
- The pack is listed as "refurbished" Can of worms right there.
- 3500mah Panasonic cells means they are GA's (thats the cell model/type). GA's are high capacity but not high output. And they get real hot when pushed, and do not handle that heat well (like 30Q's would). GA's are a good cell for low output jobs with few cells in a pack, so their 3500mah capacity maximizes that pack's capacity. So you see GA's mostly in small, low power packs.
- The details on the BMS are as follows: "installed". Not exactly above-board disclosure. Typical Panasonic GA BMS limits are 30a-35a at most but since this is a 48v refurb of an obviously low power pack I wouldn't count on anything, and this is the thing you have to count on.
